Members of a Russian crew pose on the tarmac next to a Tu-154 aircraft together with their US counterparts during an observation flight over the territory of the United States under the open Skies Treaty, July 2000. (OSCE)

Canadian officer A/Lt.Col. John Preston and Russian officer Col. Alexander Baryshnikov shake hands after signing a document as part of a Russian mission over Canada under the Open Skies Treaty, September 2004. (OSCE)

Ukrainian military personnel greeted by their Czech counterparts after a flight over the Czech Republic, April 2003, under the Open Skies Treaty, which establishes a regime of unarmed aerial observation flights over the territory of its 34 signatories. (OSCE)

Czech and Spanish military experts discus a flight over Ukraine, May 2004, under the Open Skies Treaty, which establishes a regime of unarmed aerial observation flights over the entire territory of its 34 signatories. (OSCE)